Bacterial and mammalian cells contain cell surface carbohydrate in the form of polysaccharides, glycoproteins, glycolipids, and glycosaminoglycans. Lysozyme is widely distributed in the body secretions and preliminary experiments suggest that lysozyme interacts with the carbohydrate moieties of oral bacteria to cause cell aggregation. Thus our supposition in this proposal is that lysozyme exhibits a "lectin-like" activity with both bacterial and mammalian cells. The major objective of the proposed research will be to elucidate the nature and specificity of the lysozyme cell surface carbohydrate interaction since this has been virtually unexplored. This may provide the basis for defining lysozyme biological role as a host defense factor in dental caries, periodontal disease and other pathological processes. A definitive conclusion that lysozyme can interact with and modulate the properties of human lymphocytes will have health-related implications, since the immune response is often the decisive factor between health and disease. A second objective will be to investigate the interaction of lysozyme, complement, and antibody with whole cells using antibody specific for cell surface components of oral microorganisms. The techniques used will include the following: (a) spectrophotometric and microscopic analyses of aggregation, (b) computer simulation of the aggregation process, (c) in vitro assays of lymphocyte response, (d) isolation, purification, and characterization of antigens and receptors, (e) determination of the binding affinity of lysozyme linked to an active site-directed radiolabeled irreversible inhibitor, (f) investigation of the inhibition of bacterial aggregation and lymphocyte response to lysozyme by antibodies, oligosaccharides, microbial antigens, and lymphocyte membrane components, and (g) preparation of ferritin- labeled antibody and peroxidase-labeled lysozyme for electron microscpic studies of the location of lysozyme on cell surfaces.